Hydrogen has been attracting attention environmentally as a clean energy source in view of the prevention of earth warming. In the field of vehicles, hydrogen has been widely noticed as an alternative fuel in place of hydro carbon fuels such as gasoline. Especially a vehicle (fuel cell vehicle), on which a fuel cell that generates electricity electrochemically is mounted, is in the spotlight worldwide and its development is in progress strenuously. Another vehicle powered by an internal combustion engine, which is supplied with hydrogen as fuel, is also coming up for discussion. Each of these hydrogen vehicles has a hydrogen container: either a highly pressurized hydrogen container of some tens MPa or a hydrogen container of metal hydride (MH) type employing hydrogen absorbing alloys. In the case of a hydrogen vehicle (fuel cell case), a fuel cell is supplied with hydrogen by the hydrogen container, thereby generating electricity to drive an electric motor. In the case of the other hydrogen vehicle (internal combustion engine case), the hydrogen stored in the hydrogen container burns in the internal combustion engine to produce driving power.
When the hydrogen container of each hydrogen vehicle is empty, it is necessary to load it with hydrogen. Loading of the hydrogen is performed at a hydrogen station which is equipped with a hydrogen loading unit. It is requested for the hydrogen station that a hydrogen container should be loaded with hydrogen as quickly as possible, so that a driver can handle a hydrogen vehicle like a conventional vehicle. When hydrogen loading is performed, the loading volume of hydrogen is controlled by monitoring the pressure and the temperature changes of the hydrogen container by connecting the communication lines of the hydrogen station with the hydrogen vehicle.
A hydrogen station, which loads a sizable number of hydrogen vehicles, requires a large number of large and highly-pressurized hydrogen containers (curdle etc.). Or it is necessary to install a liquefied hydrogen tank and store the evaporated hydrogen in a high-pressurized hydrogen tank such as a tank for buffering. A high power compressor is also requested. So whichever case it is, a spacious area is indispensable, resulting in an undesirably large scale facility.
It is anticipated that large scale hydrogen stations would not be dominant in view of the profitability in the beginning of hydrogen vehicles going on the market. Small scale hydrogen stations would therefore command a majority of stations in loading the hydrogen vehicles, which possibly causes the inconveniences relating to the shortage of hydrogen. So it is required for small scale hydrogen stations to load the customer vehicles with hydrogen smoothly without shortage.
It is needed urgently that the vehicles (hydrogen vehicles) on which the hydrogen containers for supplying hydrogen are mounted and which have environmental advantages such as the prevention of the earth greenhouse effect should be brought into wide use. Implementation of stable supply and smooth loading of hydrogen is prerequisite for promoting the hydrogen vehicles.